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Fracture Strength, Failure Types, and Weibull Characteristics of Three-Unit Zirconia Fixed Dental Prostheses After Cyclic Loading: Effects of Veneering and Air-Abrasion Protocols


Campos, Fernanda; Souza, Rodrigo O; Bottino, Marco A; Özcan, Mutlu (2016). Fracture Strength, Failure Types, and Weibull Characteristics of Three-Unit Zirconia Fixed Dental Prostheses After Cyclic Loading: Effects of Veneering and Air-Abrasion Protocols. International Journal of Periodontics and Restorative Dentistry, 36(6):901-908.

Abstract

The required connector dimension for zirconia fixed dental prostheses (FDPs) may be a clinical limitation due to limited space in the occlusogingival direction. Using no veneering in the gingival regions of the pontics and connectors may solve this problem. This study evaluated the mechanical durability of zirconia FDPs with and without veneering in the gingival area of the connectors and pontics and subsequent air abrasion of this region with different protocols. Models were made of resin abutments (diameter = 6 or 8 mm, height = 6 mm, 6 degrees convergence) and embedded in polyurethane resin (distance = 11 mm). Zirconia frameworks were milled and randomly distributed by veneering (veneering of the entire framework [VEN] or no veneering at gingival regions of the pontic and connector [NVEN]) and by air-abrasion (Al₂O₃/SiO₂, 30 μm; or 45 μm Al₂O₃. FDPs were adhesively cemented and subjected to mechanical cycling (1,200,000 cycles, 200 N, 4 Hz, with water cooling). Specimens were tested until fracture (1 mm/min), and failure modes were classified. Data (N) were subjected to one-way analysis of variance in two sets, Tukey test (α = .05) and Weibull analysis. While veneering did not significantly affect the results (VEN: 1,958 ± 299 N; NVEN: 1,788 ± 152 N; P = .094), air abrasion did (P = .006), with the worst results for the groups conditioned with 45 μm Al₂O₃ (SiO₂: 1,748 ± 273 N; Al₂O₃: 1,512 ± 174 N). The NVEN group demonstrated the highest Weibull modulus (12.8) compared with the other groups (5.3-7.2). Fractures commonly initiated from the gingival side of the connector. Veneering of the gingival region of the connectors and pontics in zirconia FDPs did not diminish the fracture strength, but air-abrasion of this area with 45 μm Al₂O₃ decreased the results.

Abstract

The required connector dimension for zirconia fixed dental prostheses (FDPs) may be a clinical limitation due to limited space in the occlusogingival direction. Using no veneering in the gingival regions of the pontics and connectors may solve this problem. This study evaluated the mechanical durability of zirconia FDPs with and without veneering in the gingival area of the connectors and pontics and subsequent air abrasion of this region with different protocols. Models were made of resin abutments (diameter = 6 or 8 mm, height = 6 mm, 6 degrees convergence) and embedded in polyurethane resin (distance = 11 mm). Zirconia frameworks were milled and randomly distributed by veneering (veneering of the entire framework [VEN] or no veneering at gingival regions of the pontic and connector [NVEN]) and by air-abrasion (Al₂O₃/SiO₂, 30 μm; or 45 μm Al₂O₃. FDPs were adhesively cemented and subjected to mechanical cycling (1,200,000 cycles, 200 N, 4 Hz, with water cooling). Specimens were tested until fracture (1 mm/min), and failure modes were classified. Data (N) were subjected to one-way analysis of variance in two sets, Tukey test (α = .05) and Weibull analysis. While veneering did not significantly affect the results (VEN: 1,958 ± 299 N; NVEN: 1,788 ± 152 N; P = .094), air abrasion did (P = .006), with the worst results for the groups conditioned with 45 μm Al₂O₃ (SiO₂: 1,748 ± 273 N; Al₂O₃: 1,512 ± 174 N). The NVEN group demonstrated the highest Weibull modulus (12.8) compared with the other groups (5.3-7.2). Fractures commonly initiated from the gingival side of the connector. Veneering of the gingival region of the connectors and pontics in zirconia FDPs did not diminish the fracture strength, but air-abrasion of this area with 45 μm Al₂O₃ decreased the results.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Dental Medicine > Clinic for Fixed and Removable Prosthodontics
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:December 2016
Deposited On:30 Nov 2016 15:35
Last Modified:04 Dec 2016 06:36
Publisher:Quintessence Publishing
ISSN:0198-7569
Publisher DOI:https://doi.org/10.11607/prd.2524
PubMed ID:27740655

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